Contributions to Science, Vol 10, No 1 (2014)

Margalef’s mandala, Prochlorococcus, and geoengineering

Sallie W. Chisholm

Abstract

Ocean phytoplankton played a central role in oxygenating our planet’s atmosphere billions of years ago. Hence these early “geoengineers” were crucial for the evolution of life on Earth. Their modern-day ancestor, the marine cyanobacterium Prochlorococcus, is the most abundant photosynthetic cell on the planet. Its discovery 30 years ago served as a reminder of how little we understand about the complexities of marine food webs. Yet proposals to fertilize the oceans, either to mitigate climate or enhance fi sheries, continue to gain momentum both within the scientific community and in the commercial sector. If implemented, the unintended consequences of these and other geoengineering proposals are likely to be enormous, and impossible to anticipate.

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